Creek flows in a generally southwesterly direction. The channel of the creek is sinuous and flows through rock formations consisting of sandstone and shale. Oriskany sandstone and Lower Helderberg limestone occur on Limestone Ridge near it. Oriskany cherty sandstone occurs near the confluence of the tributary Mud Creek. Additionally, Black Genesee shales have also been observed near the creek, as does the Tully limestone. Rock of the Hamilton Group is common in the area as well and is in places covered with sandstone boulders of the Pocono Formation. Hydric soils occur along it in central Montour County. In the early 1900s, the average annual rate of precipitation in the watershed of Chillisquaque Creek was . The creek has relatively warm water. Watershed The watershed of Chillisquaque Creek has an area of . The mouth of the creek is in the United States Geological Survey quadrangle of Northumberland. However, its source is in the quadrangle of Washingtonville. The creek also passes through the quadrangle of Milton. The creek can be accessed from Pennsylvania Route 45, Pennsylvania Route 405, and Pennsylvania Route 642. The watershed of Chillisquaque Creek parts of four counties: Montour County, Northumberland County, Columbia County, and Lycoming County. The portion of Montour County that is in the watershed is the central portion. It is the largest watershed in that county, accounting for 56 percent of its land area. It is also the only large stream in northern Northumberland County. There are about of streams in the watershed. The land alongside Chillisquaque Creek is mainly used for farming. As of the 1980s, the main crops are corn and soybeans. There is a gauging station on Chillisquaque Creek at Washingtonville. The area of the creek's watershed upstream of this point is . A reservoir known as Lake Chillisquaque is located on the tributary Middle Branch Chillisquaque Creek in Anthony Township, Montour County. It is the largest lake/reservoir in Montour County, with an area of . There are two dams in the watershed: the Lake Chillisquaque dam and the Montour Ash Basin No 1 dam. Both were built in 1971. The former drains an area of , while the latter drains an area of . History Chillisquaque Creek was entered into the Geographic Names Information System on August 2, 1979. Its identifier in the Geographic Names Information System is 1171784. The creek is also known as Chilisquaque Creek. Its name most likely